The present invention is concerned with the mechanism for applying pressure sensitive tape to cartons having their end and side flaps folded inward, to anchor those folded flaps securely. It is an old practice in the concerned art to provide such machines which receive from an operator's hands or equipment he controls cartons with their flaps folded over contained contents, and to apply to each carton pressure sensitive tape for securely anchoring in closed positions the folded carton flaps. These machines are equipped with tape applying assembly units each of which frequently has two tape applicator rollers that are pivotally mounted for swing. In some the unit has a single first roller projecting into a path of transport of each carton through the machine and with this roller supporting an end of the tape with its adhesively coated face opposed to the leading end wall of the on-coming carton for adherence anchorage thereto. Then, as the carton advances, it swings this first applicator roller forward to lower it out of the way of the oncoming carton while wiping the adhesive tape to anchorage of carton surfaces, i.e., first a portion of the carton leading end wall surface, then along the longitudinal top (or bottom as the case may be) to lap the opposed edges of the infolded side flaps and finally to leave a trailing end section to lap up (or down as the case may be) against the trailing carton end wall by one of the remaining pair of applicator rollers. This pair of rollers constitute with their carrying arms a sub-assembly which is pivoted to supporting frame structure of the mechanism and the carrying arm of the one thereof nearest to the first roller is linked by a coupling means to the carrying arm of this first roller, so that as the latter is depressed by advance of the carton for wiping of the tape thereby longitudinally along the carton, the swing of the first roller's carrying arm forward swings back the carrying arm of the second roller to cause the latter to repeat the wipe against the tape laid down longitudinally until the carton back wall is reached. This piece of tape is cut off by a knife pivotally supported by the first roller carrying arm and the resultant trailing free end is then wiped over the carton trailing back corner and against the carton back end wall to complete the tape application operation.
If the pressure sensitive tape is of relatively thick plastic stock it may have sufficient stiffness to resist effectively a tendency of a free severed end to flop around as it is being swung toward an advancing carton end wall, or as its back section is severed from the tape being drawn from its supply source. This flopping around of thinner such tape frequently causes portions of its adhesively coated face to engage parts of the applying mechanism for adherence thereto, and also short lengths thereof to stick and loop together, so that such tape does not adhere to the carton and ultimately an adhering tangle of fouling tape is caused which requires machine shut-down and tangle removal. Such tape is quite expensive and thus use of thinner gauges thereof can represent an appreciable cost economy, which is permitted because of the great strength of such tape even in very thin gauges.
It is thus an object of the present invention to provide such tape applying equipment with quite simple additive means which effectively reduces such flopping about tendencies and the attendant uneconomical losses of time and tape sections in an unusually economical manner while permitting the practical use of very thin and thus much cheaper pressure sensitive tape.
Another object of the present invention is to solve this problem to the satisfaction of the machine owner or user by mounting the additive means directly on the first applicator roller carrying means while avoiding any necessity for appreciable redesign of the other parts of the standardized mechanism.
A further object of the invention is to provide such additive means in a form which is quickly and economically constructed and easily installed in the basic tape applying equipment.
In accordance with the present invention a typical embodiment of the tape cartridge that has been improved by the addition thereto of equipment of this invention may have been installed in the machine base to perform as follows. A loaded carton may be pushed by hand into the entry end of the machine and it will be abutted against a control on the lowered head beam to cause side rails to be moved in to opposite sides of the carton and the head beam to be raised out of the path of the carton so that it can move forward to abut against the first wipe-on tape applicator roller. The upstanding end of the pressure sensitive tape will adhere to the front or leading end wall of the advancing carton. The continued forward travel of the carton will pull the tape off of the tape supply or roll thereof. The tension of the tape is adjustable through a brake on the core which supports the tape roll supply. As the tape is pulled through the cartridge by the advancing carton this tape travels up over means immediately preceding this first wipe-on roller for guiding the tape to and lapping its back side against this roller with shaping of the tape by transverse bowing to provide a longitudinal stiffening mid-rib in its adhesively coated face for substantially flop-free guidance of the tape to this roller's cylindrical surface. This roller cylindrical surface smoothes out the tape to substantially flat disposition by lap thereagainst for substantially flat application to opposed carton surfaces against which this roller is rolled. Preferably, this guiding means may comprise a pivoted guide plate overlaid by a tape biasing fork, with the pulled tape traveling up therebetween. This tape guide plate is spring loaded toward a stop which orients its face surface toward alignment with a tangent of this first roller cylindrical surface and the biasing fork is spring loaded back toward the guide plate surface to snug the traveling tape back against this ribbed guide plate face to bow or arch the traveling tape transversely for providing a medial crowned rib extending longitudinally along the central zone of the tape for stiffening its end section extending to the first applicator roller so as to reduce or eliminate any tendency to flop about. The uncoated back side of the tape rides over a convexed transverse ridge at the back end of the tape guide plate which prevents the tape from wrinkling. The pair of transversely spaced fingers of the fork drag lightly against the adhesively-coated tape face on opposite sides of a longitudinal convexed and central rib.